JP2002021092A - No-loading caisson method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a no-loading caisson method capable of lessening the size of a soil improvement body for a sea-bottom ground and delivering a reduction in construction cost and construction period in caisson type revetment works and the like. SOLUTION: The simple soil improvement body 12 only for supporting a temporary caisson is built in the sea-bottom ground 11 in the installation position of the caisson 1. The caisson 1 formed precedently with a vertically penetrating through hole 3 is settled to be temporarily supported by the body 12. A foundation pile 4 is driven through the through hole 3 into the sea-bottom ground 11, and the caisson 1 is jacked up. After that, a shearing key 6 is mounted on the upper end part of the foundation pile 4, bentonite mortar 14 is injected between the bottom surface of the caisson 1 and the surface of the sea-bottom ground 11, and mortar 16 is injected between the through hole 3 and the foundation pile 4 for the purpose of fixing the caisson 1 to the upper part of the foundation pile 4 and supporting the finished caisson by the foundation pile 4 without imposing any loads on the sea-bottom ground 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unloaded caisson construction method for building a caisson-type seawall.

[0002]

2. Description of the Related Art For example, when a caisson type revetment structure as a gravity type structure is built on a soft submarine ground, conventionally, as shown in FIG. The ground is improved, and the caisson 1 is installed on the ground improvement body 50. The ground improvement body 50 prevents the caisson 1 after completion from sinking for a long time.

[0003]

However, in the case of the conventional caisson as described above, the ground improvement body 50 supports the vertical force due to the weight of the caisson and the back earth pressure, so that the ground improvement body 50 is large. However, there is a problem that the construction cost and the construction period increase.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to reduce the size of a ground improvement body on the seabed in caisson type revetment, thereby reducing the construction cost and the construction period. It is an object of the present invention to provide a non-loaded caisson construction method that can achieve the above.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when a caisson is installed at a predetermined position on the seabed, a simple ground improvement body which only supports the caisson at the time of temporary installation on the seabed at the installation position of the caisson is constructed. A caisson with a through hole penetrating vertically is settled and temporarily supported by the ground improvement body, and then a foundation pile is driven into the seabed ground through the through hole, and the caisson is fixed on the upper part of the foundation pile And the completed caisson is supported by the foundation pile for a long time.

The ground improvement body may be partially built below the caisson. However, the ground improvement body is built corresponding to the position of the foundation pile through hole of the caisson, and the foundation pile is driven into the ground improvement body at each location. It is preferable to do so.

The caisson can be fixed to the upper part of the foundation pile by various fixing methods.
Jack up the caisson using the foundation pile as a guide, attach a locking member such as a shear key at the upper end of the foundation pile, fill the gap between the bottom of the caisson and the surface of the seabed ground with filler such as bentonite mortar, It is preferable that a gap between the through hole and the foundation pile is filled with a filler such as mortar and the caisson is fixed to the upper part of the foundation pile.

In the above configuration, the caisson at the time of completion is supported by the foundation pile, so that the caisson structure has no load on the seabed ground, and the ground improvement body temporarily supports the caisson at the time of temporary construction. Only a simple and small ground improvement body is required, and the construction cost and construction period can be reduced. The surrounding lateral flow and settlement can be dealt with by a simple ground improvement body. After the caisson is installed, the foundation pile can be driven by using the through hole of the caisson as a guide, so that the foundation pile can be easily driven without using a template. Further, the ground improvement body is constructed corresponding to the position of the foundation pile, and the foundation pile is driven into the ground improvement body, whereby the foundation pile can be reinforced. The caisson structure can be easily unloaded on the seabed by jacking up the caisson and fixing it to the upper part of the foundation pile with a shear key or bentonite mortar.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. This embodiment is an example in which a caisson type seawall is newly constructed on an existing seawall.
FIGS. 1, 2 and 3 show an example of an unloaded caisson when the present invention is completed. FIG. 4 shows an unloaded caisson method of the present invention in the order of steps.

As shown in FIGS. 1 to 3, a caisson 1 used in the unloaded caisson method of the present invention is made of concrete or the like, and has a rectangular bottom plate 1a in plan view and a bottom plate 1a.
a is formed in the shape of a box with an upper part opened by an outer wall 1b integrally rising from the four circumferences of FIG. a, and as shown in FIG. 2, its interior is formed of six chambers 1d by partition walls 1c arranged vertically and horizontally in plan view. Is divided into

In such a caisson 1, as shown in FIG. 2, a total of six pillars 1e are formed inside the caisson by thickening the four corners and the center of the long side of the outer wall 1b. As shown in FIG. 1, a through hole 3 penetrating vertically is provided by embedding an extracorporeal tube 2. The inner diameter of the through hole 3 is made larger than the outer diameter of the foundation pile 4 made of a steel pipe pile or the like so that the foundation pile 4 can be inserted from above.

The outer periphery of the upper end of the outer tube 2 is shown in FIG.
As shown in (c), a bearing plate 5 having an L-shaped cross section is buried so that its upper surface is flush with the concrete surface, and receives the lower end surface of a shear key 6 attached to the outer periphery of the upper end of the foundation pile 4. Avoid damage to concrete. In addition,
The extracorporeal tube 2 and the bearing plate 5 are buried when the caisson is manufactured.

The ground improvement body 12 built on the seabed ground 11 below the caisson 1 may be a simple ground improvement body that only supports the caisson 1 at the time of temporary construction. For example, the column improvement 1e of the caisson 1 (through hole) A total of six pipes are located below 3), and a cylindrical body having a ring-shaped cross section surrounding the foundation pile 4 to be cast is formed by a deep mixing method using a cement-based hardener.

The foundation pile 4 has a lower part which is sufficiently penetrated into a support layer (not shown) of the seabed ground 11 and an upper part which has a length sufficiently protruding from the upper end surface of the caisson 1. Is jacked up by a predetermined amount as a guide, and then a bentonite mortar filled in the gap between the bottom surface of the caisson 1 and the upper surface of the seabed 11, and the shear key 6 attached to the outer peripheral surface of the upper end of the foundation pile 4 By filling the caisson 1 with 14 and filling the mortar 16 between the through hole 3 and the foundation pile 4, the caisson 1 is fixed to the upper part of the foundation pile 4 and supported by the foundation pile 4.

As shown in FIG. 1B, for example, as shown in FIG. 1 (b), a total of four shear keys 6 are arranged at equal intervals in the circumferential direction of the foundation pile 4, and are fixed vertically by welding or the like. As shown in FIG. 1 (a), a grout stopper 13 is provided in the gap between the bottom surface of the caisson 1 and the top surface of the submarine ground 11 so as to surround the outer periphery of the caisson 1. Foundation pile 4
A mortar stopper 15 is provided in a gap between the mortar stopper 15 and the mortar stopper 15.
In addition, fixing of caisson 1 and foundation pile 4 is not limited to this,
Other fixing methods may be employed.

In the above configuration, the no-load caisson method is performed in the following procedure (see FIG. 4).

(1) A caisson 1 having a through hole 3 is manufactured in a manufacturing yard or the like. The manufactured caisson 1 is towed to a predetermined installation position.

(2) A simple ground improvement body 12 is constructed on the seabed ground 11 at the caisson installation position adjacent to the existing revetment 10 so as to correspond to the position of the through hole 3 of the caisson 1.

(3) When the construction of the ground improvement body 12 is completed,
The caisson 1 that has been towed is settled and settled on the ground improvement body 12.

(4) The foundation pile 4 is inserted into the through hole 3 of the caisson 1 and is driven through the center of the ground improvement body 12.

(5) The caisson 1 is jacked up by a predetermined amount. A shear key 6 is attached to the outer peripheral surface of the upper end of the foundation pile 4. After a grout stopper 13 is installed in the gap between the bottom surface of the caisson 1 and the top surface of the seabed ground 11 so as to surround the outer periphery of the caisson 1, bentonite mortar 14 is injected into the gap. A mortar stopper 15 is installed in a gap between the lower end of the through hole 3 and the foundation pile 4, and mortar 16 is injected between the through hole 3 and the foundation pile 4.
Caisson 1 consists of shear key 6 and bentonite mortar 1
4 and the mortar 16 in the through hole 3
And is supported by the foundation pile 4.

(6) Each room 1e of the caisson 1 is filled with filling sand 17 if necessary, and then an upper concrete 18 is poured on the upper part of the caisson 1 to form the foundation pile 4 and filling sand 17
Cover the top of The revetment is completed by reclaiming the space between the existing revetment 10 and caisson 1 to form a reclaimed land 19.

The completed caisson revetment structure is supported by the foundation pile 4 and a simple ground improvement body 12, and the submarine ground 1
No load is applied to 1 and long-term settlement and the like are reliably prevented. Since the ground improvement body 12 may be simple enough to support the caisson 1 at the time of temporary construction, the amount of the ground improvement body is greatly reduced, and the construction is extremely simple.

Although the revetment has been described above,
The present invention is not limited to this, and can be applied to other caisson-type harbor structures.

[0025]

Since the present invention has the above-described configuration, the following effects can be obtained.

(1) Since the completed caisson is supported by the foundation pile, the caisson structure has no load on the seabed ground, and the ground improvement body is simple enough to temporarily support the caisson at the time of temporary construction. In this case, a small ground improvement body is sufficient, and the construction cost can be reduced and the construction period can be shortened.

(2) After the caisson is installed, the foundation pile can be driven using the through hole of the caisson as a guide, so that the foundation pile can be easily driven without using a template. This makes it possible to build a caisson structure at low cost in a short period of time.

(3) The ground improvement body is constructed corresponding to the position of the foundation pile, and the foundation pile is driven into the ground improvement body.
The foundation pile can be reinforced and a stable caisson structure can be obtained.

(4) The caisson is jacked up and fixed to the upper part of the foundation pile with a shear key or bentonite mortar or the like, whereby the caisson structure can be easily unloaded on the seabed ground.

[Brief description of the drawings]

1 shows an example of a completed unloaded caisson according to the present invention, in which (a) is a cross-sectional view, (b) is a plan view of an upper part of a foundation pile, and (c) is a foundation pile. It is an expanded sectional view of an upper part.

FIG. 2 is a plan view of the unloaded caisson of FIG. 1;

FIG. 3 is a longitudinal sectional view of the unloaded caisson of FIG. 1;

FIG. 4 is a sectional view showing the unloaded caisson method of the present invention in the order of steps.

FIG. 5 is a cross-sectional view showing an example of a revetment work by a conventional caisson method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Caisson 1a ... Bottom plate 1b ... Outer wall 1c ... Partition wall 1d ... Room 1e ... Column part 2 ... Extrapolation tube 3 ... Through hole 4 ... Foundation pile 5 ... Bearing plate 6 ... Shear key 10 ... Existing Seawall 11 ... Seabed ground 12 ... Soil improvement 13 ... Grout stopper 14 ... Bentonite mortar 15 ... Mortar stopper 16 ... Mortar 17 ... Filled sand 18 ... Top concrete 19 ... Reclaimed land

Claims (1)

[Claims] When a caisson is installed at a predetermined position on a seafloor ground, a ground improvement body is constructed on the seafloor ground at the installation position of the caisson, and a caisson having a through-hole that penetrates up and down in advance is settled to settle the ground improvement. A non-loaded caisson, wherein the caisson is temporarily supported by a body, and then a foundation pile is driven into the seabed through the through hole, and a caisson is fixed to the foundation pile and the completed caisson is supported by the foundation pile. Construction method.